Several people have reported having the problem of the contents of an object never loading in the Edit window. One specific cause has been isolated: ByteFence Anti-Malware. If you have this program installed (and please note that it may have come pre-installed on your computer, or bundled with some other product), then try uninstalling it. See this page for instructions.
If you do not use this product, then one thing to check is whether you are being affected by region lag. So try going to a known low lag region where build is allowed, such as here, and see whether the issue persists there. If object contents load normally there, then the region you were working in before, likely has high lag, or issues of some other kind and may need restarting.
Otherwise, you may have connection-related problems. For that, try rebooting your network hardware (router and/or modem), then your computer. Other tips may be found here.